<!DOCTYPE html>
<html lang="en">
	<head>
		<meta charset="UTF-8" />
		<meta http-equiv="X-UA-Compatible" content="IE=edge" />
		<meta name="viewport" content="width=device-width, initial-scale=1.0" />
		<title>Document</title>
		<style>
			.item {
				position: fixed;
				width: 100px;
				height: 100px;
				left: 0;
				right: 0;
				background-color: #f00;
			}
			.box2 {
				left: 20px;
				top: 20px;
				background-color: #0f0;
				z-index: -1;
			}
			.box3 {
				left: 40px;
				top: 40px;
				background-color: #00f;
			}
			.info {
				position: absolute;
				z-index: 9999;
			}
		</style>
	</head>
	<body>
		<div class="item box1">1</div>
		<div class="container">
			<div class="item box2">
				<div class="info">哈哈</div>
			</div>
		</div>
		<div class="item box3">3</div>
	</body>
</html>
